WINDOWS 10, firewall file missing

Windows 10 cannot be updated. Error message 0x800706d9. Firewall is not running and when I try to reset to defaults I get a message that there are Firewall file(s) missing. Microsoft "trouble" scan can't detect or repair. Still using version 1511 because it's unable to update Windows 10 (dozens of updates have failed). Performance is pathetic especially when trying to enter text for emails. Sometimes I have to wait for minutes before it will allow me to continue.

Try running sfc /scannow to see if it restores any missing system files. After the scan finishes reboot the system and try updating.